No, those are claims that have been made throughout the years. I've heard it from various collectors and others over the years.
Supposedly the heat treating process that S&W was using at the start of US entry into the war was one of the major reasons that S&W couldn't get its production up to the levels demanded by the US military and contributed directly to the Army's take over of the plant in 1918.
There's some interesting tidbits in this discussion at the S&W Forums...
http://smith-wessonforum.com/s-w-hand-ejectors-1896-1961/145722-heat-treated-m-1917-cylinders.html
There's also some contradictory information on heat treating in this discussion:
http://elfishingmusician.blogspot.com/2010/05/shooting-impressions-smith-and-wesson.html
My understanding however, is that it works out this way...
When introduced, the New Century Triple Lock (the basis for the N frame 1917) chambered the relatively low-pressure .44 Special round and didn't really require much in the way of heat treating.
When the British requested revolvers in .455 Webley for their war effort, the same was true. The .455 also operated in the same pressure range as the .44 Special, or right around 15,000 psi.
When S&W started production of .45 ACP 1917s for the US military, it was quickly found that the .45's operating pressure of 21,000 psi, combined with the S&Ws relatively thin chamber walls, was causing problems with cylinder damage.
This is, according to some, the genesis of S&W's heat treating of the cylinders as well as the opening up of the chamber mouths to reduce pressure.
Someone above posited that the primary reason for this was because of the FMJ bullets. That's an interesting though, but I know of no issues with the barrels on early S&W 1917s -- all reported issues were with the cylinders and frames.
There are also reports of British/Canadian S&Ws chambered in .455 coming back into the United States being converted to .45 ACP when .455 became unavailable suffering cracked or blown cylinders. This is the same kind of problem that many have run into with Webley revolvers converted to .45 ACP -- the operating pressure of the .45 round is simply too high for the guns originally chambered in .455.
Anyway, do I have proof positive? No. Just a lot of interesting tidbits that point toward some very interesting conclusions.